Plant for evacuating dredged material

ABSTRACT

A plant for evacuating dredged material is disclosed, according to which the dredged material, in form of aqueous suspension of high solid content, is loaded into transporting lighters, of the type comprising a closed loading cavity, having an upper loading inlet and a lower discharge connection, and the lighters shuttle between the dredging apparatus and a flow floating station, provided with at least a pneumatic pump, per se known, and with means for connecting the intake duct of said pump with said discharge connection of the lighter.

United States Patent 1 Faldi May 6, 1975 [54] PLANT FOR EVACUATINGDREDGED 3,426,715 2/1969 l14/27 MATERIAL 3,528,462 9/1970 Quase........141/284 3,595,278 7/1971 Lilly et 141/1 [76] Inventor: Giovanni Faldi,via Forese Donati 27, F1 t 1 Creme 1 a y Primary Examiner-R1chard E.Aegerter Filedi Apr. 3, 1973 Assistant ExaminerFrederick R. SchmidtAppl. No.: 347,373

Foreign Application Priority Data May 17, 1972 Italy 24498172 US. Cl.141/284; 114/27; 141/312; 141/388; 214/13; 214/15 B Int. Cl B631) 35/30Field of Search 61/721; 114/27, 36; 141/1, 67,113, 279, 284, 287, 311,312,

References Cited UNlTED STATES PATENTS Jessup 114/36 Attorney, Agent, orFirm-Karl W. Flocks [57] ABSTRACT A plant for evacuating dredgedmaterial is disclosed, according to which the dredged material, in formof aqueous suspension of high solid content, is loaded into transportinglighters, of the type comprising a closed loading cavity, having anupper loading inlet and a lower discharge connection, and the lightersshuttle between the dredging apparatus and a flow floating station,provided with at least a pneumatic pump, per se known, and with meansfor connecting the intake duct of said pump with said dischargeconnection of the lighter.

4 Claims, 6 Drawing Figures F SEE'MEE HAY 819. 5

SHEH 30? 6 I I I I u I I PMENTEU HAY 5 SHEET 5 OF 6 1 PLANT FOREVACUATING DREDGED MATERIAL The present invention relates to a plant fordischarging and transporting to a distance refuse material of semi-solidor pulp form, particularly suitable for material dredged from submergedbeds.

In dredging marine or lacustrine beds, the essential problem alwaysexists of eliminating the dredged material. In particular, when thedredging plant is mounted on floating pontoons or watercraft, recourseis normally made to transporting lighters which are filled with thedredged material and shuttle between the dredging zone and the zone inwhich discharge takes place.

However this system is subject to various disadvantages, mainly of aneconomical nature and relating to the length of the operations.

In fact normally the material loaded into the lighters, especially ifpumped with dredges provided with impeller pumps, contains a very highpercentage of water in order to permit loading and especially dischargewith normal pumping plants. is evident that the superfluoustransportation to a distance of such a large quantity of water affectsthe costs of the dredging operations. In addition, as the zones to bedredged are normally fairly extensive, the journey which the lightershave to make is usually fairly long. As these are relatively slowwatercraft, it is clear that this influences the length of the dredgingoperations or the investment costs in terms of number of watercraft.

Finally in some cases, where the purpose of the dredging is also to freethe bed from polluting and dangerous material, for example hydrocarbonsludge, mercury compounds and others, the dredged material must beloaded on to lighters and transferred a great distance in order to avoidnew pollution of the same dredged zone or others adjacent. In thesecases moreover it is unadvisable to use buckets which by moving the bedwould cause a second pollution, aided by the currents.

Dredging plants exist (the subject of previous patents and patentapplications by the same applicant), mounted on pontoons and consistingof pumping units provided with dredging shovels which are submerged, thedredging shovels of which engage with the bed, disaggregating it andconveying the material towards pumping chambers or cylinders operatingby compressed air, and from which the material mixed with water isconveyed to the surface by means of a flow pipe. The main advantage ofthese dredging plants is the flexibility of application, both in termsof the depth of dredging and of the type of bed dredged, plus a highdredging efficiency and a reduced water content of the dredged material.

Flow plants are also known, and constitute the subject of a previouspatent application by the same applicant, in which pneumatic pumps ofthe same type as the aforementioned are used in combination with loadingtanks for conveying to a distance material in the form of an aqueoussuspension of high solid content. These plants are particularly usefulfor conveying to a distance industrial waste, and for example for thereclaiming of beaches and the like.

It has now been found, and constitutes the main object of the presentinvention, that the problems briefly mentioned previously are completelyresolved to great advantage by a plant for conveying and discharging ata distance dredged material in the form of an aqueous suspension, inwhich the dredged material is loaded into distance transportinglighters, of the closed type, characterised in that it comprises afloating flow station provided with a plurality of pneumatic flow pumps,the inlet pipe of each pump being arranged for removable connection tothe outlet of a transporting lighter suitable for shuttling between thedredging plant and said flow station, further characterised in that saidlighter, provided or not provided with autonomous drive means, comprisesa completely closed loading cavity in which an upper aperture isprovided for loading the dredged material, and a discharge connectionsituated on the bottom at one end of said cavity, in which there arealso provided means for conveying to said connection the dredgedmaterial which fills the cavity of the lighter, and from there by way ofa flexible pipe to said inlet pipe.

In a first particularly preferred embodiment of the present invention,said means for conveying the dredged material which fills the loadingcavity of the lighter consist of a conveying shovel mobile within thecavity from a position at the end of the lighter furthest from said endin which said discharge connection is formed, to this latter end of saidcavity.

In a further embodiment of the invention, usable in particular when thedredged material has a lower percentage of solids, said conveying meansconsist of a header situated inside said cavity along its longitudinalaxis, said header comprising a plurality of apertures distributed alongits axis such as to allow the gradual discharge of the dredged material,one end of said header being connected to said discharge connection.

In a further preferred embodiment of the present invention, the flowstation is characterised, besides the submerged flow pump, also bycomprising a mooring system for the lighters, provided with fixedmooring points for disposing the lighter and in particular its dischargeconnection in a predetermined required position with respect to thesubmerged pump, and also in that means are provided for bringing theinlet pipe of the submerged pump into tight communication with thedischarge connection of the lighter.

One of the main advantages of the present invention lies in the factthat it is possible to convey the dredged material away from thedredging zone with minimum transportation costs by lighters, andtransporting a minimum quantity of superfluous water, since theconcentration of solids in the dredged material transported by thelighters and pumped by the flow station can reach A further similarlyimportant advantage is that by this system, the dredged material passesfrom the dredging pump to the discharge zone without any loss, and henceif it should be polluted any repollution is consequently avoided.

A further advantage is that the mooring and discharge operations of thelighters at the flow station are facilitated and made rapid,independently of the conditions of the sea, lake, river and the like.

These and further aspects and advantages of the present invention willbe more evident from the following description given in relation to theaccompanying drawings in which:

FIG. 1 is a schematic view of the plant according to the presentinvention;

FIG. 2 is an analogous view of the plant in the working stage;

FIG. 3 is a view of a detail of a possible variation;

FIGS. 4 and 5 are a frontal and lateral schematic view respectively ofthe particular embodiment of the flow station for the mooring anddischarge of the lighters loaded with dredged material, of which FIG. 6shows a variation.

FIG. 1 shows the essential parts of the plant according to the presentinvention, i.e. the transporting lighter B and the pumping station P.

This latter comprises a floating pontoon 10 on which are mounted the aircompressor and distributor 12 for the operation of the submerged pumpingunit 13.

This latter, suspended by a cable 16 from a support arm 14, comprises aplurality of pneumatic pumping chambers or cylinders (normally three innumber) to which, according to a sequence determined by the distributor12 of known type, compressed air arrives through the pipe 17, whereasthe pipes 18 and 19 constitute the inlet and discharge respectively forthe dredged material.

The cable 20, which is adjustable, supports the flanged connection endof the pipe 18.

It must be emphasised that the floating pontoon or platform P maycomprise a plurality of submerged pumping units 13, according to thecapacity of the plant and especially of the hourly capacity of thedredging section.

As the operation of the pumping unit is well known from previoustechnology, no detailed description will be given of it.

Considering now the transporting lighter B, this comprises a hull 21with an internal cavity 22 for filling with the dredged material 23,closed upperly by a cover or bridge 24 comprising a funnel loading mouth25 (possibly closable by a gate valve) so as to avoid the emergence ofpolluting gases which are released from the dredged material.

At one end of the cavity 22 is provided a flanged discharge connection26, to which a flexible pipe 27 is connected, its free end beingsuspended in an adjustable manner by means of a cable 28 from a raisingarm 29 mounted on the bridge 24. Within the cavity 22 is mounted aconveying shovel 30, mobile along the longitudinal axis of the lighterby means of dragging cables 31 passing around intermediate pulleys 32and driven by the winch 33. Return cables 34 are driven by the winch 35.

As seen clearly from FIGS. 1 and 2, the front surface of the shovel 30is shaped so as to cause the dredged material 23 to be conveyed towardsthe discharge connection 26.

Considering in particular FIG. 2, when the lighter B has been broughtclose to the pumping station P, the two ends of the pipes 27 and 18 areconnected, after which the winch 33 is operated and the shovel 30 isdragged towards the other end of the cavity 22, so causing in thismanner the discharge of the material 23 which alternately fills thevarious cylinders of the pneumatic pumping unit 13, from which thematerial 23 is made to flow to the required distance.

It has been found in this manner that the material 23 may reach a solidcontent of up to 85%, a figure which enables the advantage attained bythe present invention to be completely appreciated.

Suitable sliding guides are provided for the sliding of the shovel 30.Any equivalent solution may also be provided, for example the dischargeconnection 26 in a central position and two symmetrical shovels whichapproach from the ends towards the centre.

Furthermore, any analogous system, for example a system with pneumaticor hydraulic pistons, may be employed for pushing the shovel 30 duringthe discharge stage of the dredged material 23.

FIG. 3 shows a variation concerning essentially the lighter and usefulin those cases in which the dredged material has a less high solidcontent and hence a considerably lower viscosity. In this case, forconveying the dredged material to the outside of the cavity 22, a pipeor header 36 is fitted provided with apertures 37 through which thedredged and fairly fluid material passes by gravity into the pumpingcylinders of the pneumatic pumping station P.

In the plant described with reference to FIGS. 1-3, the discharge pipeconnected to the discharge connection of the lighter must be connectedto the inlet pipe of the submerged flow pump. This system has theadvantage of flexibility and rapidity of transfer from one place of workto another, jointly with the movements of the actual dredging plant, butin practice a certain time may be necessary for connecting the twosections of pipe, as they are normally of a certain size and hence noteasily manageable, especially under rough sea conditions.

The purpose of the modification shown in FIGS. 4 and 5 is to make theconnecting operations much more rapid, even though it requires a morecomplex and preferably fixed installation, which is however economicallyjustified in the case of work of a certain size, because of the savingin time, the saving of labour and the possibility of removing theconnecting operation from dependence on the ability of the operators.The principle on which the system shown in FIGS. 4 and 5 is based isthat of providing mooring points for the lighters so that they arealways in the correct position with respect to the submerged flow pump.

For this purpose the lighter 21 has its discharge connection 26controlled by a discharge valve 50 (in its turn controlledhydraulically, pneumatically or manually), provided with a wide flange51 against which the flat flange 52 complete with a rubber seal gasket53, and at which the inlet pipe 18 of the submerged pump 13 finishes, istightly fitted. The flange 52 constitutes the final part of a funnelconnection 54 to which the pipe 18 is generally coaxially fixed. Thefunnel connection 54 is in its turn rigid with an annular floatingelement 55, preferably a tubular ring full of air and having such avolume as to guarantee the tendency of the entire assembly (tubularring, funnel and inlet pipe of the pump) to float.

As can be seen in FIGS. 4 and 5, the floating tubular element isanchored at the bottom by a set of four cables 56 controlled by way ofintermediate pulleys 57 by four synchronised drums 58 or a single winchwith four drums. Both the pulleys S7 and winches 58 are mounted eitheron two palisade structures 59, preferably of the type comprisingfoundation piles 60 sunk into the bed and supporting the platfonns 61,which also support the other equipment necessary both for the operationof the submerged pump (motor driven compressor, distributor etc.) andfor its raising and lowering (for example shears and cable) or on twopontoons provided with retractable legs resting on the marine bed.

The palisade structure or pontoons 59 form a corridor of predetermineddimensions into which one or more lighters enter one after the other andmoor in a precise predetermined central position with respect to thefloating assembly comprising tubular ring, funnel and flange.

For this purpose it is necessary that all lighters have the sameexternal shape (possibly comprising some external facing of wood or thelike) so that they may be moored in said corridor and each dischargeconnection be located at the said respective floating assembly.

The operation of this variation of the present invention is as follows:

When the lighter arrives in the discharge zone it is directed by its ownmeans or is pushed into the corridor formed between the two palisadestructures until it strikes against a point of arrest previouslyconstructed (indicated by the reference numeral 62) so giving theassurance that the discarge connection 26 and relative plate 51 lie in aposition corresponding with the funnel which tends to rise by the actionof the floating tubular ring full of air. Any slight differences may beneglected in that the funnel has an inlet mouth of much greater diameterthan the diameter of the discharge connection of the lighter.

The floating assembly (floating tubular ring, pipe and funnel) will beanchored below the bottom of the lighter when it arrives, by the set ofcables 56. When the lighter has been anchored at the correct point, theraising winch is operated so as to enable the inlet pipe of the pump tobe raised and hence the terminal cone or funnel by the action of thefloating tubular ring until the plate of the cone rests with its rubbergasket on the plate surrounding the discharge pipe positioned on thebottom of the lighter.

When the cables 56 which pull the floating tubular ring downwards becomeslack, this signifies that there is perfect adhesion between the twoplates and hence the discharge valve may be opened and the emptying ofthe lighter and pumping to a distance may be commenced.

As the lighter empties it tends because of its smaller weight to floatto a greater extent and raise itself from the water, but as the cablesof the four drum winch or the four synchronised winches are idle, thefloating tubular ring automatically maintains the contact between thecone and discharge tube by rising, so avoiding any dispersion ofmaterial, which may be polluted, into the zone where the work is carriedout.

When the lighter has been emptied, operations are carried out in thereverse direction, i.e. firstly the discharge valve is closed, then bymeans of the four drum winch or the four synchronised winches thefloating tubular ring is pulled downwards while continuing to pump for ashort period of time so as to completely clean the inlet pipe and pumpbody.

As soon as the funnel and relative plate of the discharge pipe have beensufficiently removed, the lighter may be immediately re-transported backto the dredging plant.

If it is thought that the material with which the lighter is filled isnot sufficiently fluid, one of the systems described hereinafter may beapplied in order to facilitate unloading, or water may be added by asuitable pump.

Obviously the corridor which has been described as formed from palisadestructures may also be constructed in the form of two or a series ofstrong pontoons provided with retractable legs for resting on the bed orfrom pontoons firmly anchored, but this system is less practical in thecase of zones with large tide differences, because it requires thecontinual variation of the length of the cables fixing the pipes whichwould have to maintain a perfectly rigid corridor for the entry of thelighters.

instead of using means for forming a corridor, in some cases it ispossible using the same means (platform on palisade, pontoon onretractable legs or anchored pontoon) to obtain the same results bybringing the lighter or lighters to the side of these means, which inthis case would act as a quay.

FIG. 6 shows diagrammatically the modification in which instead of acorridor a mooring pontoon is pro vided, to which the lighters to bedischarged are brought alongside.

The embodiment of FIG. 6 can be more practical and more easily adaptableeven in the case of open sea, especially using pontoons with retractablelegs, because it avoids disturbances due to the difference in level ofthe tide, and the need to construct fixed works which are difficult torecover, and further it enables very rapid dislocation both at thebeginnig and at the end of the work in the case of a sea storm.

For this purpose it is sufficient to provide the pontoons with asuitable system for raising the conveyed pump body and the relativefloating and conveying equipment so that it may be raised withoutaltering the profile of the watercraft in the water and hence withouthindrance to its movement.

A further solution especially for lighters which are not self-propelledand which would enable one or more lighters to be easily towed by asingle tug, or with a further tug at the rear in the case of a number oflighters, and which facilitates a more rapid mooring, is represented byone or more pontoons in a row so as to construct a quay, moored eitherby means of anchorages or on retractable legs resting on the bed, inwhich the pump body and the systems for raising the floating tubularring to be applied to the bottom of the lighter are firmly supported bythe pontoons.

Previously the floating tubular ring has been shown always full of airand pulled downwards at the end of operations by a winch and cables, butthe system may be equally realised by emptying the tubular ring of theair and filling it with water when the inlet cone is to be lowered, andcarrying out the reverse operation when it is to be raised.

From the foregoing description it will be clear that the presentinvention provides an excellent solution to the problem of eliminatingdredged material, especially enabling the wasteful transport and flow oflarge quantities of water to be avoided and reducing considerably theshuttle times of the lighters.

Although explicit reference has been made to dredging plants, otherapplications of the plant according to the invention are not excluded,for example for eliminating industrial waste, if in the form of asuspension in a liquid.

What I claim is:

1. A plant for conveying and discharging at a distance dredged materialin the form of an aqueous suspension, in which the dredged material isloaded into lighters at a dredging station for transport to a distance,characterized in that said plant comprises a floating flow pumpingstation provided with at least one and preferably a plurality ofsubmerged pneumatic flow pumps, having, respectively, a plurality ofinlet pipes at least one transporting lighter selectively operativelyconnected to or disconnected from said floating flow pumping station,said transporting lighter having a discharge connection, the inlet pipeof each pump being removably connected to the discharge connection ofthe transporting lighter arranged for shuttling between the dredgingstation and said floating flow pumping station, further characterized inthat said lighter, provided preferably with its own drive means,comprises a completely closed loading cavity with an upper aperture forreceiving the dredged material and a discharge aperture situated in thebottom of the cavity, said discharge aperture being arranged forconnection by way of said discharge connection to said flow pump inletpipe in said floating station, means provided in said cavity forconveying the dredged material filling said cavity towards saiddischarge aperture, said flow station comprises in addition to at leastone submerged pneumatic flow pump a mooring corridor for the lighters,provided with fixed mooring points such as to dispose the lighter and inparticular its discharge connection in a predetermined position withrespect to the submerged pump and in which are further provided meansfor bringing the inlet pipe of the submerged pump into tightcommunication with the discharge connection of the lighter, and saidmeans for bringing the inlet pipe of the submerged pump into tightcommunication with the discharge connection of the lighter comprising apart shaped as a funnel generally coaxial with said inlet pipe and rigidwith the free end of said inlet pipe, said funnel part terminating in aflat flange fitted with a seal gasket, arranged to mate with a flatflange formed on the bottom of the lighter at and concentric with saiddischarge connection, and means anchored adjustably downwards and rigidwith said funnel part to ensure that the funnel part floats.

2. A plant as claimed in claim 1, in which said mooring corridorcomprises palisade elements anchored to the bed of a body of water andsupporting two platforms on which the necessary equipment for theoperation of the submerged pump is mounted.

3. A plant as claimed in claim 2, in which said means which ensure thatthe funnel part floats consist of an annular tube element suitable forfilling with air, cables fixed to said tube element and operativelyconnected to synchronised members mounted on said platforms and by whichsaid float may be pulled downwards by said synchronised members.

4. A plant as claimed in claim 1, in which said mooring corridorcomprises two or more floating pontoons provided with telescopic legsfor resting on the bed of a body of water so as to make the entireassembly stable, said pontoons being adapted to support equipmentassociated with said pump.

1. A plant for conveying and discharging at a distance dredged materialin the form of an aqueous suspension, in which the dredged material isloaded into lighters at a dredging station for transport to a distance,characterized in that said plant comprises a floating flow pumpingstation provided with at least one and preferably a plurality ofsubmerged pneumatic flow pumps, having, respectively, a plurality ofinlet pipes at least one transporting lighter selectively operativelyconnected to or disconnected from said floating flow pumping station,said transporting lighter having a discharge connection, the inlet pipeof each pump being removably connected to the discharge connection ofthe transporting lighter arranged for shuttling between the dredgingstation and said floating flow pumping station, further characterized inthat said lighter, provided preferably with its own drive means,comprises a completely closed loading cavity with an upper aperture forreceiving the dredged material and a discharge aperture situated in thebottom of the cavity, said discharge aperture being arranged forconnection by way of said discharge connection to said flow pump inletpipe in said floating station, means provided in said cavity forconveying the dredged material filling said cavity towards saiddischarge aperture, said flow station comprises in addition to at leastone submerged pneumatic flow pump a mooring corridor for the lighters,provided with fixed mooring points such as to dispose the lighter and inparticular its discharge connection in a predetermined position withrespect to the submerged pump and in which are further provided meansfor bringing the inlet pipe of the submerged pump into tightcommunication with the discharge connection of the lighter, and saidmeans for bringing the inlet pipe of the submerged pump into tightcommunication with the discharge connection of the lighter comprising apart shaped as a funnel generally coaxial with said inlet pipe and rigidwith the free end of said inlet pipe, said funnel part terminating in aflat flange fitted with a seal gasket, arranged to mate with a flatflange formed on the bottom of the lighter at and concentric with saiddischarge connection, and means anchored adjustably downwards and rigidwith said funnel part to ensure that the funnel part floats.
 2. A plantas claimed in claim 1, in which said mooring corridor comprises palisadeelements anchored to the bed of a body of water and supporting twoplatforms on which the necessary equipment for the operation of thesubmerged pump is mounted.
 3. A plant as claimed in claim 2, in whichsaid means which ensure that the funnel part floats consist of anannular tube element suitable for filling with air, cables fixed to saidtube element and operatively connected to synchronised members mountedon said platforms and by which said float may be pulled downwards bysaid synchronised members.
 4. A plant as claimed in claim 1, in whichsaid mooring corridor comprises two or more floating pontoons providedwith telescopic legs for resting on the bEd of a body of water so as tomake the entire assembly stable, said pontoons being adapted to supportequipment associated with said pump.